processor-affinity-mask

Arguments:

Windows only.

The processor affinity in Windows is a number which specifies the
number of processors (i.e. chips) that will be used by the running
process. In Allegro CL 7.0, the best affinity is 1 and
there are known problems with higher affinities. The startup code on
Windows sets the affinity to 1.

This function is defined on Windows versions only. It uses a Microsoft
routine which is documented as working on Windows NT/2000/XP. (On
Unix versions, the symbol exists but has no function definition.)

On Windows, return the current process' processor affinity mask (a
non-negative integer). It does this by calling
GetProcessAffinityMask(), and an error is signaled if
this routine returns an error (0).

setf'ing sys:processor-affinity-mask

The setf value is the new
processor affinity mask--see the Microsoft documentation on
SetProcessAffinityMask(). Our startup code sets the
mask to 1 (see the (internal) function
start-lisp-execution defined in [Allegro
directory]/src/aclstart.cl). An error is signalled if the call to
SetProcessAffinityMask() fails.